The present invention relates to IR detection and imaging, and more particularly to IR imaging with acoustic surface wave readout.
A pyroelectric material is one that is characterized by the presence of a spontaneous polarization at room temperature with no applied electric field. This spontaneous polarization is a function of temperature with the pyroelectric coefficient, p, given by EQU p=(dP/dT ), (1)
where P is the spontaneous polarization (charge density) on the material and T is the temperature.
If the pyroelectric material is first doped with an appropriate impurity, such that a suitable carrier concentration, n, is achieved in the pyroelectric material, there will exist a depletion zone (absence of free charge carriers) at the surface. This depletion zone will be due to the presence of the surface charge repelling the free charge carriers from the surface. The depth of the depletion zone is a function of the surface charge density which is in turn a function of the temperature of the surface as indicated by equation(1).